4. We aren't emotionally connected to what we're saying. We may be reciting a report or going through a scripted talk we've given dozens of times in the past, and our lack of excitement results in non-stop, often monotonal diatribe that leaves the audiences as bored as we are.
I've copied only the fourth reason, the implications of which stun me. Click through for five more reasons (and some fine analysis) from Rich Hopkins.
More from Rich on this topic.